This project will evaluate the increase in information content to be obtained by systematically integrating into one three- dimensional reconstruction, the densitometric information available from multi-view coronary artery angiograms. It will determine the relationship between information content (i.e. accuracy and precision in the vessel positioning length, and lumen cross-section measurements) and number of views used in performing the reconstruction. The project will develop techniques to use multiple views to improve accuracy in cross- section measurements and to refine measures of vessel asymmetry. Ultimately the project will test the hypothesis that three-dimensional reconstruction can be used to reduce the number of views required in clinical angiography and thereby reduce the risk of the procedure. Algorithms already developed include automated tracking of the major branches of the coronary vascular bed throughout the heart cycle, reconstruction of the beating centerline and cross-section of the coronary tree from two views, and densitometric (and shaded surface) display of the reconstructed images. This project will extend the algorithm to include information from arbitrary numbers of views in the 3D reconstruction. Accuracy and precision will be determined from reconstructions of precisely constructed and machined vessel phantoms. A static vessel phantom will consist of branching vessels of various sizes (from 10mm down to 0.5mm), each having asymmetric lesions in the range of 30% to 90%. To assess the effects of motion, flexible and pulsating vessel structures will also be used. Accuracy and precision in reconstructions of clinical cardiac images will be determined by comparing the segments of vessels from the 3D reconstruction with measurements obtained using standard geometric techniques. Standard statistical tests such a regression analysis and analysis of variance will be used to determine the significance of the measurement comparisons. This project will be followed by a later study to develop techniques of absolute coronary blood flow measurements and to assess the hemodynamic effects of three-dimensional vascular anatomy. These latter phases depend on technique to measure the absolute vascular dimensions (cross-section as a function of distance along each branch) of the major branches of interest.